Robust cross-linked polyurethane elastomers with reprocessing capabilities and flame-retardant from renewable vanillin
Tongshuai Tian, Teng Zhang, Ling Lei, Tianyi Han, Li Liu
Abstract
The majority of polymers are derived from non-renewable fossil fuels, and the rapid consumption of these resources has raised serious concerns regarding climate change, environmental pollution, and public health. Furthermore, a common trait of traditional petroleum-based polymers is their high flammability. Given the urgent challenges associated with traditional petroleum-based polymers regarding safety and environmental protection, it is essential to develop recyclable and flame-retardant bio-based cross-linked polyurethane (PU) elastomers derived from renewable resources. This is crucial for achieving sustainable development and ensuring material safety throughout their lifecycle. In this study, a novel and multi-functional hexahydric alcohol (PV-OH) incorporating multiple flame retardant groups and reversible imine bond structure was synthesized from vanillin. This alcohol was employed to develop cross-linked PU elastomers (PPUs) with outstanding reprocessing ability and fire resistance performance, based on Polyester oligomer. The mechanical properties, thermal properties, and flame retardancy of the samples improved significantly with an increase in PV-OH content. The obtained PPUs exhibited relatively low activation energy (35.2∼50.6 kJ/mol) and remarkable hot-pressed remolding efficiency (∼100 %). Additionally, the cyclotriphosphazene groups and imine bond structures in polymer chains impart exceptional flame-retardant performance to PPUs, with the PPU-40 achieving a V-0 rating in the UL-94 vertical burning test and displaying a LOI of 29.2 %. This study presents a straightforward and innovative approach to manufacturing multifunctional bio-based cross-linked PUs with potential applications in various fields.